1000 —> Leap Year
1001 —> Not Leap Year
1002 —> Not Leap Year
1003 —> Not Leap Year
1004 —> Leap Year
1005 —> Not Leap Year
1006 —> Not Leap Year
1007 —> Not Leap Year
1008 —> Leap Year
1009 —> Not Leap Year
1010 —> Not Leap Year

You find leap years for any year ranges by changing the $start and $end.